The present invention relates to a two-cycle engine and, more particularly, to a two-cycle engine employing a balancing shaft and wherein an engine casing is provided in which an intake passage, a crank chamber and a transmission chamber are integrally formed.
A large number of two-cycle engines carried by vehicles, such as motorcycles, motor three wheelers, or the like, are provided with an engine casing in which an intake passage, a crank chamber and a transmission chamber are integrally formed. Such engines are also provided with a balancer shaft which is used for cancelling oscillations due to the reciprocatory movements of the pistons, the connecting rod, or the like. In such two-cycle engines, as for example the one disclosed in Japanese Patent Laid-Open No. 62-13761 (No. 13761/1987), both of the intake passage and the balancer shaft are arranged above the line which connects the axis of the crank shaft with the axis of the main shaft of the transmission mechanism in which the power of the crank shaft is input to the axis of the main shaft. Consequently, the conventional structure of these engines is not intended to lower the center of gravity of the engine. Also, in such engines incorporating a structure wherein reed valve is located in the intake passage, because of the problem of balancer shaft interference with the reed valve, limitations are imposed when designing the reed valve.